You'll likely get a lot more forum votes for spinning plates (because it seems to be the "in" cool thing to say at the moment).
As to which is better.... I think that it's more a matter of personal preference. Personally, I haven't lately met any women that would inspire me toward monogamy, but I like this setting - when it occurs.
I'm thinking that more forum members have been in relationships than regular multi-dating...and so, I'll comment on the randomness.
Below are con's that I've experienced.
1. The more you sleep around, the more likely you may get the clap. I was luckier than some and less lucky than some. Back in my 20's, I caught HPV, but haven't had an issue in over 30 years.
2. It's easy to confuse names and their stories. I've screwed up by saying "how was your tennis game?" It was the wrong gal. I've screwed up like this several times (women may know that they aren't the only one, but they don't care for blatant reminders).
3. It can get expensive. While some women will drop by to "hang out" , some want to go out. If you're doing this 4-5 times a week, it can add up.
4. You'll also end up doing more laundry. Women can just 'tell' if pillow cases/sheets have been occupied by another woman.
5. You'll probably not be as sharp at work (if you two are drinking and/or pulling an all-nighter in the sack) it can catch up with you at work (if doing this several times during the week).
In addition to the obvious benefits, here are the bonuses.
1. It's good for the ego.
2. Friends will envy you.
3. If they are dropping by, they sometimes bring beer.
4. If you're bored or other plans fall through, there's less effort in making something happen or having a "plan B."
5. Sometimes you get invited over for home cooked meals (which will lead to 'other things') .
6. If one gal has a quality that's slightly irritating, the next girl probably doesn't have this trait (but she may have an irritating quality that the one the night before didn't possesses.)
The above are just a few things to consider. There could be more that I've either forgotten or haven't personally experienced.